Motor Dynamics Encoding in Cat Cerebellar Flocculus Middle Zone During Optokinetic Eye Movements

1999 ◽  
Vol 82 (5) ◽  
pp. 2235-2248 ◽  
Author(s):  
Toshihiro Kitama ◽  
Tomohiro Omata ◽  
Akihito Mizukoshi ◽  
Takehiko Ueno ◽  
Yu Sato
Keyword(s):  
Time Course ◽  
Inverse Dynamics ◽  
Coefficient Of Determination ◽  
Eye Position ◽  
Middle Zone ◽  
Forward Selection ◽  
Optokinetic Response ◽  
Position Information ◽  
Stimulus Velocity ◽  
Cerebellar Flocculus

We investigated the relationship between eye movement and simple-spike (SS) frequency of Purkinje cells in the cerebellar flocculus middle zone during the optokinetic response (OKR) in alert cats. The OKR was elicited by a sequence of a constant-speed visual pattern movement in one direction for 1 s and then in the opposite direction for 1 s. Quick-phase-free trials were selected. Sixty-six cells had direction-selective complex spike (CS) activity that was modulated during horizontal (preferring contraversive) but not vertical stimuli. The SS activity was modulated during horizontal OKR, preferring ipsiversive stimuli. Forty-one cells had well-modulated activity and were suitable for the regression model. In these cells, an inverse dynamics approach was applied, and the time course of the SS rate was reconstructed, with mean coefficient of determination 0.76, by a linear weighted superposition of the eye acceleration (mean coefficient, 0.056 spikes/s per deg/s2), velocity (5.10 spikes/s per deg/s), position (−2.40 spikes/s per deg), and constant (mean 34.3 spikes/s) terms, using a time delay (mean 11 ms) from the unit response to the eye response. The velocity and acceleration terms contributed to the increase in the reconstructed SS rates during ipsilateral movements, whereas the position term contributed during contralateral movements. The standard regression coefficient analyses revealed that the contribution of the velocity term (mean coefficient 0.81) was predominant over the acceleration (0.03) and position (−0.17) terms. Forward selection analysis revealed three cell types: Velocity-Position-Acceleration type ( n = 27): velocity, position, and acceleration terms are significant ( P < 0.05); Velocity-Position type ( n = 12): velocity and position terms are significant; and Velocity-Acceleration type ( n = 2): velocity and acceleration terms are significant. Using the set of coefficients obtained by regression of the response to a 5 deg/s stimulus velocity, the SS rates during higher (10, 20, and 40 deg/s) stimulus velocities were successfully reconstructed, suggesting generality of the model. The eye-position information encoded in the SS firing during the OKR was relative but not absolute in the sense that the magnitude of the position shift from the initial eye position (0 deg/s velocity) contributed to firing rate changes, but the initial eye position did not. It is concluded that 1) the SS firing frequency in the cat middle zone encodes the velocity and acceleration information for counteracting the viscosity and inertia forces respectively, during short-duration horizontal OKR and 2) the apparent position information encoded in the SS firing is not appropriate for counteracting the elastic force during the OKR.

Properties of superior vestibular nucleus neurons projecting to the cerebellar flocculus in the squirrel monkey

1993 ◽  
Vol 69 (2) ◽  
pp. 642-645 ◽  
Author(s):  
Y. Zhang ◽  
A. M. Partsalis ◽  
S. M. Highstein
Keyword(s):  
Eye Movement ◽  
Squirrel Monkey ◽  
Vestibular Nucleus ◽  
Squirrel Monkeys ◽  
Eye Position ◽  
Oculomotor Nucleus ◽  
Position Sensitivity ◽  
Cerebellar Flocculus ◽  
The Mean ◽  
Superior Vestibular Nucleus

1. Properties of superior vestibular nucleus (SVN) neurons and their projection to the cerebellar flocculus were studied in alert squirrel monkeys by using chronic unit and eye movement recording and microstimulation techniques. Twenty-three cells were antidromically activated from the ipsilateral flocculus, and seventeen of these were also orthodromically activated from the ipsilateral VIIth nerve at monosynaptic latencies. Only 1 of these 23 units was also inhibited by flocculus stimulation. According to their response properties, 9 of the cells were pure vestibular, 2 were vestibular-pause, and 12 were position-vestibular cells. The mean eye position sensitivity of these position-vestibular cells was significantly lower than that of cells projecting to the oculomotor nucleus (OMN). No eye movement-only neurons were antidromically activated from the flocculus. No cells could be antidromically activated from both the oculomotor nucleus and the flocculus.

Corollary discharge provides accurate eye position information to the oculomotor system

Science ◽  
1983 ◽  
Vol 221 (4616) ◽  
pp. 1193-1195 ◽  
Author(s):  
B. Guthrie ◽  
J. Porter ◽  
D. Sparks
Keyword(s):  
Oculomotor System ◽  
Corollary Discharge ◽  
Eye Position ◽  
Position Information

Evaluating the Statistical Significance of Models Developed by Stepwise Regression

1983 ◽  
Vol 20 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Shelby H. McIntyre ◽  
David B. Montgomery ◽  
V. Srinivasan ◽  
Barton A. Weitz
Keyword(s):  
Monte Carlo ◽  
Null Hypothesis ◽  
Regression Models ◽  
Stepwise Regression ◽  
Statistical Significance ◽  
Selection Procedure ◽  
Coefficient Of Determination ◽  
Forward Selection ◽  
Monte Carlo Simulation Study ◽  
Independent Variables

Information for evaluating the statistical significance of stepwise regression models developed with a forward selection procedure is presented. Cumulative distributions of the adjusted coefficient of determination ([Formula: see text]) under the null hypothesis of no relationship between the dependent variable and m potential independent variables are derived from a Monté Carlo simulation study. The study design included sample sizes of 25, 50, and 100, available independent variables of 10, 20, and 40, and three criteria for including variables in the regression model. The results reveal that the biases involved in testing statistical significance by two well-known rules are very large, thus demonstrating the desirability of using the Monté Carlo cumulative [Formula: see text] distributions developed by the authors. Although the results were derived under the assumption of uncorrelated predictors, the authors show that the results continue to be useful for the correlated predictor case.

Postsaccadic eye position contributes to oculomotor error estimation in saccadic adaptation

2019 ◽  
Vol 122 (5) ◽  
pp. 1909-1917
Author(s):  
Svenja Gremmler ◽  
Markus Lappe
Keyword(s):  
Visual Feedback ◽  
Eye Position ◽  
Time Interval ◽  
Proprioceptive Information ◽  
Experimental Conditions ◽  
Position Information ◽  
Saccadic Adaptation ◽  
Position Signal ◽  
Motor Error ◽  
Saccade Control

We investigated whether the proprioceptive eye position signal after the execution of a saccadic eye movement is used to estimate the accuracy of the movement. If so, saccadic adaptation, the mechanism that maintains saccade accuracy, could use this signal in a similar way as it uses visual feedback after the saccade. To manipulate the availability of the proprioceptive eye position signal we utilized the finding that proprioceptive eye position information builds up gradually after a saccade over a time interval comparable to typical saccade latencies. We confined the retention time of gaze at the saccade landing point by asking participants to make fast return saccades to the fixation point that preempt the usability of proprioceptive eye position signals. In five experimental conditions we measured the influence of the visual and proprioceptive feedback, together and separately, on the development of adaptation. We found that the adaptation of the previously shortened saccades in the case of visual feedback being unavailable after the saccade was significantly weaker when the use of proprioceptive eye position information was impaired by fast return saccades. We conclude that adaptation can be driven by proprioceptive eye position feedback. NEW & NOTEWORTHY We show that proprioceptive eye position information is used after a saccade to estimate motor error and adapt saccade control. Previous studies on saccadic adaptation focused on visual feedback about saccade accuracy. A multimodal error signal combining visual and proprioceptive information is likely more robust. Moreover, combining proprioceptive and visual measures of saccade performance can be helpful to keep vision, proprioception, and motor control in alignment and produce a coherent representation of space.

Normal and Adapted Visuooculomotor Reflexes in Goldfish

1997 ◽  
Vol 77 (3) ◽  
pp. 1099-1118 ◽  
Author(s):  
Eric Marsh ◽  
Robert Baker
Keyword(s):  
Visual Stimulus ◽  
Visual Motion ◽  
Visual Stimuli ◽  
Adaptive Plasticity ◽  
Visual Training ◽  
Optokinetic Response ◽  
Stimulus Velocity ◽  
Visuomotor Behavior ◽  
Distributed Circuits ◽  
Eye Velocity

Marsh, Eric and Robert Baker. Normal and adapted visuooculomotor reflexes in goldfish. J. Neurophysiol. 77: 1099–1118. Under normal physiological conditions, whole field visual motion generally occurs in response to either active or passive self-motion. In the laboratory, selective movement of the visual surround produces an optokinetic response (OKR) that acts primarily to support the vestibuloocular reflex (VOR). During visual world motion, however, the OKR can be viewed as operating independently over frequency and amplitude ranges insufficient for vestibular activation. The goal of the present study was to characterize this isolated behavior of the OKR in goldfish as an essential step for studying central neuronal correlates of visual-vestibular interactions and the mechanisms underlying oculomotor adaptation. After presentation of either binocular sinusoidal or step visual stimuli, conjugate eye movements were elicited with an amplitude and phase profile similar to that of other vertebrates. An early and a delayed component were measured with different dynamics that could be altered independently by visual training. The ensuing visuomotor plasticity was robust and exhibited five major characteristics. First, the gain of both early and delayed components of the OKR increased >100%. Second, eye velocity decreased 0.5–2.0 s before the change in direction of stimulus velocity. Third, on lengthening the duration of a constant velocity visual stimulus (e.g., from 8 to 16 s), eye velocity decreased toward 0°/s. This behavior was correlated with the direction and period as opposed to the frequency of the visual stimulus (“period tuning”). Fourth, visual stimulus training increased VOR eye velocity with a ratio of 0.6 to 1 to that measured for the OKR. Fifth, after OKR adaptation, eye velocity consistently oscillated in a conjugate, symmetrical fashion at 2.4 Hz in the light, whereas in the dark, a rhythmical low-amplitude eye velocity occurred at the visual training frequency. We conclude that the frequency and amplitude of visual stimuli for eliciting the goldfish OKR are well suited for complementing the VOR. Unlike most mammals, OKR adaptive modifications significantly alter VOR gain, whereas the effects of VOR training are much less on OKR gain. These observations suggest that both distributed circuits and discrete neuronal populations control visuo- and vestibulomotor performance. Finally, the existence of a rhythmic, “period tuned” visuomotor behavior provides a unique opportunity to examine the neuronal mechanisms of adaptive plasticity.

Role of the cervico-ocular reflex in the “flying” pigeon: Interactions with the optokinetic reflex

2004 ◽  
Vol 21 (2) ◽  
pp. 167-180 ◽  
Author(s):  
M. MAURICE ◽  
H. GIOANNI
Keyword(s):  
Time Course ◽  
Reverse Direction ◽  
Slow Phase ◽  
Phase Lag ◽  
Optokinetic Stimulation ◽  
Optokinetic Response ◽  
Velocity Amplitude ◽  
Ocular Reflex ◽  
Optokinetic Reflex ◽  
Cervical Stimulation

We studied the cervico-ocular reflex (COR) alone and in combination with the optokinetic (OKN) reflex in head-fixed pigeons. We analyzed these responses in two behavioral conditions: (1) animals were hung in a harness (“resting” condition); and (2) animals were additionally submitted to a frontal airflow that provoked a flight posture (“flying” condition). In both conditions, cervical stimulation provoked a slow phase of very low gain (around 0.05) in the opposite direction to that of the stimulation and fast phases triggered near the head–body alignment in the same direction as the stimulation. The slow phase showed a phase lag of 20 deg at 0.5 Hz. The gain of the slow phase was not modified by the velocity, amplitude, or frequency of the stimuli. This gain was not changed by the presence of a fixed visual surround.When cervical stimuli (0.05–0.5 Hz) were added to an optokinetic stimulation (30 deg/s) in the “resting” condition, the slow phase velocity (SPV) of the optokinetic reflex was modulated with a time course close to that produced by the cervico-ocular reflex alone. The SPV was alternately increased and decreased round the SPV level corresponding to the steady-state OKN. In the “flying” condition, optokinetic-cervical stimulation provoked an eye beating field and a strong SPV modulation synchronized with the position of the cervical stimulation. The number of nystagmic beats (OKN) and the amplitude and velocity of the fast phases were modulated in correlation with the SPV. Consequently, the optokinetic response was increased or decreased according to whether the cervical stimuli were in the reverse direction or in the same direction as the optokinetic stimulation, respectively.These data are interpreted as an improvement of gaze stabilization by the COR. This mechanism is context dependent, since it is strongly reinforced during the flight.

Inflow as a source of extraretinal eye position information

1972 ◽  
Vol 12 (2) ◽  
pp. 221-IN7 ◽  
Author(s):  
Alexander A. Skavenski
Keyword(s):  
Eye Position ◽  
Position Information

Product Distributions of Benzene Alkylation with Propylene Estimation Using Artificial Neural Network (ANN)

2013 ◽  
Vol 772 ◽  
pp. 227-232
Author(s):  
Xiao Yan Sun ◽  
Shu Guang Xiang
Keyword(s):  
Time Course ◽  
Coefficient Of Determination ◽  
Alkylation Reaction ◽  
Data Sets ◽  
Bp Network ◽  
Benzene Alkylation ◽  
Model Catalysis ◽  
Product Distributions ◽  
Artificial Neural ◽  
Trained Network

The usability of artificial neural networks (ANN) for the estimation of the product distributions was investigated. The study was performed by following a model catalysis reaction, benzene alkylation with propylene on zeolite MCM-22. The effects of temperature, the ratio of benzene/propylene (B/P) and weight hourly space velocity (WHSV) on the product distributions were studied. Data obtained from different courses were used for training of the ANN and one set of data obtained from another courses was used for testing of the trained network. This network was designed as a Back-Propagation (BP) network with four neurons in the input layer, N neurons in the hidden layer and one neuron in the output layer. The network was trained till the mean square value between the targets and the outputs obtained was 1×10-4. The product distributions for the isopropylbenzene, di-isopropylbenzene and tri-isopropylbenzene were estimated using the trained network. The regression coefficient of determination showed a good correlation between estimated and experimental data sets for both train and test data sets. There are high correlations between experimental and estimated time course curves and that was another proof of the high performance of ANN for estimation of the product distributions of alkylation reaction.

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